Ethmomaxillary sinus.

Ethmomaxillary sinus is a variation of the posterior ethmoid cells. It is formed by the extension of the posterior ethmoid cells into the maxillary sinus and drains into superior nasal meatus. It is incidentally seen on paranasal sinus computerized tomography (CT) scans. Its prevalence has been reported as 0.7 and 2% in two studies. In this study, paranasal CT scans of 466 patients were investigated for the presence of ethmomaxillary sinus. The patients had paranasal CT with the preliminary diagnoses of septal deviation, chronic inflammatory paranasal sinus disease and nasal turbinate disorders. The ethmomaxillary sinus was present in nine of those patients (1.93%). It was septated in one of them. The CTs were further investigated for other anatomical variations and co-existent mucosal disease of the paranasal sinuses.